This invention relates to a trocar used for introducing an endoscope, forceps, electric cautery or other device into a body cavity in surgery under the endoscope.
In recent years, surgery under the endoscope which excises the gallbladder or anastomose the intestine without incision of the abdomen is performed in practice. This technique is a low-invasion surgery without incision of the abdomen. Therefore, a long hospitalization is not needed and the burden of a patient is light.
A trocar is a surgical instrument used for puncturing the abdomen and inserting an endoscope, forceps, electric cautery, or other surgical instrument into the abdomen, and typically comprises a trocar tube (cannula) and a trocar needle (blade) with a sharp-pointed front end. When used, a trocar with the trocar needle held in the trocar tube is thrust into the abdominal cavity through the body wall with the front end of the trocar needle (blade), and then the blade alone is pulled out leaving the trocar tube to permit the insertion of a surgical device such as an endoscope, forceps, or electric cautery into the abdominal cavity.
Surgery under the endoscope conventionally perzbrmed is described here using FIG. 12, a sectional view which illustrates the technique of surgery under the endoscope. In surgery under the endoscope, a space for operation is made in the abdominal cavity 118 by stabbing an air-injecting needle through the body wall 117 and injecting a gas such as CO.sub.2 to inflate the abdominal cavity or by skewering the body wall with a wire and pulling up the body wall. Next, a small incision is made in the body wall 117, and a trocar is thrust into the incision and the trocar needle (not shown) is pulled out leaving the trocar tube. Then, an endoscope 119 such as a flexible or rigid scope is inserted into the abdominal cavity 118 through the path secured by means of the trocar tube 113. Long operative devices such as a forceps 114, grasping forceps 115, and electric cautery 116 are also inserted through the paths secured by means of trocar tubes 113 in the same manner, and excision of the gallbladder or anastomosis of the bowel is performed watching the image on the monitor screen taken by the endoscope.
This type of trocar tube is conventionally made of a high-rigidity material such as a stainless steel or hard resin. Therefore, devices which can pass through the trocar tube are limited to slender rod-like devices with a dianmeter or breadth smaller than the inside diameter of the trocar tube.
On the other hand, a flexible trocar tube which is made of a resilient material and permits the insertion of a curved device is described in E.P.A. 535,974.
Although this trocar tube makes the insertion of a curved device through it possible, the one with an inside diameter suited to the outside diameter of the device inserted must be used, because the inside diameter is uniform throughout the length. A surgeon stabs a plurality of trocar tubes of different diameters suited to the operative devices used for the operation into the body cavity beforehand according to the contents of the operation performed. It sometimes happens that the inside diameter of some trocar tube is too small to insert an operative device or to take out the excised organ or tissue. In that case, a trocar tube of a laraer inside diameter must be stabbed, causing the problems that the number of the trocar tubes used increases, that the time required for the operation is prolonged, and that the operation becomes troublesome.
Further, since the trocar tube has a diameter sufficiently large to permit the insertion of operative devices at its front end, the front end of the trocar tube receives a considerable resistance when the trocar is thrust into the body wall hindering the thrust, and an excoriation about the same size as the diameter is left.
This invention was made to solve these problems with conventional trocars.
The first object of this invention is to provide a low-invasion trocar tube through which various operative devices can be inserted, is easy to thrust into the body wall, and does not leave a large excoriation, and a trocar equipped with such a trocar tube. Further, since conventional trocars are constructed so that only the pointed end portion of the inner needle projects from the trocar tube when the trocar needle is put in the trocar tube coaxally, they have problems that the front end of the trocar tube catches on the body wall and pulls in the body wall, causing a large resistance to the thrust when the trocar is thrust into the body wall.
The second object of this invention is to provide a trocar needle which is less invasive, exerts a smaller pulling force on the body wall, and has a smaller resistance to the thrust, and also to provide a trocar equipped with the trocar needle.